Real-time impulse-based simulation of rigid body systems for haptic display

To date, haptic interfaces have rarely been used to display complex virtual environments such as those involving 3D mechanical assembly operations, or the use of hand tools. Of the limitations which have been encountered, one is the absence of suitable simulation techniques which provide a general, user-defined virtual environment. This paper discusses the use of an impulse-based simulation as a general purpose multibody simulator for haptic display. This technique uses Poisson's hypothesis in conjunction with Coulomb friction as the basis of the contact model. Since haptic displays are required to run in real time with a constant step size and high update rate, changes to the algorithm are required. We identify the `impact state' as a critical feature of the contact model, and outline the various ways it can be chosen. Finally, we describe the implementation of a planar multibody simulator on one and two-axis haptic displays.